filer only talk to the master leader

weed/server/master_grpc_server.go

@@ -9,6 +9,7 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/topology"
 	"google.golang.org/grpc/peer"
 	"fmt"
+	"github.com/chrislusf/raft"
 )
 
 func (ms *MasterServer) SendHeartbeat(stream master_pb.Seaweed_SendHeartbeatServer) error {
@@ -105,7 +106,8 @@ func (ms *MasterServer) SendHeartbeat(stream master_pb.Seaweed_SendHeartbeatServ
 	}
 }
 
-// KeepConnected keep a stream gRPC call to the master. Used by filer to know the master is up.
+// KeepConnected keep a stream gRPC call to the master. Used by clients to know the master is up.
+// And clients gets the up-to-date list of volume locations
 func (ms *MasterServer) KeepConnected(stream master_pb.Seaweed_KeepConnectedServer) error {
 
 	req, err := stream.Recv()
@@ -113,6 +115,10 @@ func (ms *MasterServer) KeepConnected(stream master_pb.Seaweed_KeepConnectedServ
 		return err
 	}
 
+	if !ms.Topo.IsLeader() {
+		return raft.NotLeaderError
+	}
+
 	// remember client address
 	ctx := stream.Context()
 	// fmt.Printf("FromContext %+v\n", ctx)